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THE  CITY 


AND  THE 


ALLEGHENY  RIVER 
BRIDGES 


PITTSBURGH  CIVIC  COMMISSION 
191O 


. 


PITTSBURGH  Civic  COMMISSION 


THE  CITY 


AND 


THE  ALLEGHENY  RIVER  BRIDGES 


RECOMMENDATIONS  FOR  BRIDGE 
HEIGHTS  AND  PIER  LOCATIONS 
TO  MEET  THE  VARIOUS  TRANSPOR- 
TATION NEEDS  OF  PITTSBURGH 

BY 

/ 

Colonel  Thomas  W.  Symons 
Frederick  Law  Olmsted 


PREPARED  UNDER  THE  DIRECTION  OF  THE 

Committee  on  City  Planning 

324  FOURTH  AVENUE  APRIL  1910 


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CITY  AND 


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CONTENTS. 


PAGE 

INTRODUCTION    5 

RECOMMENDATIONS    .* 7 

FULL  REPORT   8 

AMOUNT  AND  IMPORTANCE  OF  TRAFFIC  AFFECTED 9 

Bridge  Traffic    9 

River   Traffic    II 

Comparison  of  Bridge  and  River  Traffic 14 

EFFECT  OF  VARIOUS  SOLUTIONS  14 

Effect  of  Various  Possible  Bridge  Heights  upon 

the  Traffic  Over   Bridges    15 

Highway   Bridges    15 

Railroad   Bridges    19 

Effect  of  Different  Bridge  Heights  upon  River  Traffic.  19 

CONCLUSIONS  AS  TO  CLEARANCE  HEIGHTS  25 

PIERS  AND  CHANNELS   26 

CONSIDERATIONS  AGAINST  REQUIRING  CHANGES  IN  BRIDGES 

TO  BE  MADE  AT  PRESENT  28 

RECOMMENDATIONS 29 

APPENDIX  I — AMOUNT  AND  IMPORTANCE  OF  BRIDGE  TRAFFIC. 31 

Highway    Bridges    31 

Railroad    Bridges    33 

APPENDIX  II — AMOUNT  AND  VALUE  OF  ALLEGHENY  RIVER 

TRAFFIC    34 


German  Side  Wheel  Boat,  Common  on  European  Rivers. 


Design  of  Boat  for  American  Rivers,  Adapted  from  European  Models. 


INTRODUCTION. 


March  I5th,  1910,  upon  recommendation  of  the  Committee 
on  City  Planning,  the  Pittsburgh  Civic  Commission  authorized 
Colonel  Thomas  W.  Symons,  Corps  Engineers,  U.  S.  A.  retired, 
and  Mr.  Frederick  Law  Olmsted  to  make  a  report  upon  desirable 
heights  and  pier  locations  for  bridges  over  the  Allegheny  River. 
The  purpose  of  the  Commission  was  to  secure  a  report  which 
weighed  the  interests  of  all  parties  to  the  bridge  question,  and 
which  would  strike  a  balance  to  meet  the  various  transportation 
needs  of  Pittsburgh. 

The  Commission  asked  the  Committee  on  City  Planning  to 
direct  the  preparation  of  the  report.  The  Committee  consists 
of  T.  E.  Billiquist,  chairman,  Charles  F.  Chubb,  H.  J.  Heinz, 
Benno  Janssen,  Richard  Kiehnel,  E.  K.  Morse.  This  committee 
passed  upon  the  report  April  i8th  and  recommended  it  to  the 
Commission  for  adoption.  On  April  25th  the  Commission  re- 
ceived and  adopted  the  report  and  voted  their  hearty  appreciation 
of  the  work  of  Colonel  Symons,  Mr.  Olmsted  and  the  Com- 
mittee on  City  Planning. 


REPORT. 

RECOMMENDATIONS. 

1.  That  the  Sixteenth  street  and  Forty-third  street  bridges 
which  are  obstructions  to  navigation  on  account  of  their  pier 
locations,  narrow    channels,  and    exceptionally    low    clearance 
height  be  required  to  be  rebuilt  with  their  piers  so  located  as  to 
give  channels  conforming  to  the  neighboring  bridges,  and  that 
their  elevation  be  fixed  with  regard  to  eliminating  the  railroad 
grade  crossings  on  their  approaches,  but  the  minimum  clearance 
shall  be  fixed  in  accordance  with  the  closing  paragraph  below. 

2.  That  the  Ninth  street  bridge  should  be  rebuilt  as  soon 
as  practicable  with  a  central  pier  and  two  wide  spans  conform- 
ing to  those  of  the  Sixth  street  and  Seventh  street  bridges.   The 
design  of  the  new  Ninth  street  bridge,  however,  should  not  be  fin- 
ally determined  and  erection  begun  until  a  definite  plan  for  com- 
prehensive improvements  in  the  traction  system  between  the  two 
sides  of  the  river  has  been  decided  upon.     Unless  new  circum- 
stances develop  before  the  construction  of  this  bridge  is  begun 
that  materially  affect  the  problem  of  clearance  height,  the  eleva- 
tion should  be  fixed  in  accordance  with  the  closing  paragraph 
below. 

3.  That  all  questions  pertaining  to  changing  the  elevation 
of  the  Sixth  street,  Seventh  street,  Fort  Wayne,  Thirtieth  street 
and  Junction  Railroad  bridges  be  deferred  to  await  the  report  of 
the  Pittsburgh  Flood  Commission  and  the  resultant  action;  to 
await  the  report  on  a  comprehensive  plan  for  traction  improve- 
ments ;  to  await  the  completion  of  the  work  projected  by  the  city 
in  cutting  down  some  streets  and  filling  others,  and  to  await  the 
results  of  investigation  of  river  boat  design  and  construction 
provided  for  in  the  river  and  harbor  bill  just  passed  by  Congress. 

4.  That  if  it  is  deemed  essential  and  necessary  at  present 
to  decide  upon  the  elevation  to  which  all  Allegheny  river  bridges 
must  be  made  to  conform,  this  elevation  be  fixed  so  that  there 
shall  be  a  clear  head  room  of  substantially  37  feet  above  pool 
level,  varied  so  as  to  give  at  each  bridge  a  clear  head  room  of 
28  feet  when  .the  river  is  at  a  15  foot  flood  stage.     This  height 
to  be  maintained  over  the  entire  main  span  where  there  is  a  cen- 
tral span  and  for  180  feet  on  each  side  of  the  central  pier  where 
there  is  a  central  pier. 

7 


FULL  REPORT. 

April   igth,   1910. 
The  Pittsburgh  Civic  Commission — 

Gentlemen: — In  accordance  with  your  expressed  desire  we 
have  examined  into  the  bridge  problem  on  the  Allegheny  river 
now  before  the  city,  particularly  in  regard  to  the  use  of  the 
bridges  and  their  connections  with  the  streets  of  the  city  and  the 
use  of  the  river  for  harbor  and  navigation  purposes,  and  beg  to 
submit  the  following  report  thereon : 

REPORT. 

There  are  three  great  interests  concerned  in  the  problem 
of  the  bridges  over  the  Allegheny  river  at  Pittsburgh ;  ( i )  those 
who  frequently  cross  the  river  or  whose  business  requires  the 
transportation  of  workmen,  raw  and  manufactured  material, 
and  supplies  from  one  side  of  the  river  to  the  other;  (2)  those 
concerned  in  the  navigation  of  the  river  and  harbor,  and  (3) 
those  who  own  and  operate  the  bridges. 

In  the  hearings  recently  held  on  the  subject  much  consid- 
eration has  been  given  to  the  bridge  owners  and  the  navigation 
interests  but  comparatively  little  attention  has  been  given,  at  first 
hand,  to  the  interests  of  the  general  public  who  in  great  numbers 
are  interested  in  transportation  across  the  river  and  for  whose 
service  both  the  bridges  and  river  transportation  exist. 

It  is  quite  apparent  from  a  study  of  the  situation  and  the 
interests  involved  that  changes  might  be  demanded  in  the  bridges 
which  would  give  some  added  advantage  to  river  navigation,  but 
yet  would  place  so  great  a  burden  upon  the  interests  concerned 
in  crossing  the  river  that  the  result  would  be  a  net  loss  to  the 
general  public.  The  following  are  the  two  extreme  positions 
somewhere  between  which  all  concerned  would  agree  that  a  bal- 
ance of  interests  most  beneficial  to  the  general  public  must  be 
determined : 

From  the  view  point  of  traffic  across  the  river  the  best  ar- 
rangement would  be  level  bridges  at  the  grade  of  the  connecting 
streets,  regardless  of  river  traffic.  The  more  the  bridges  are 

8 


caised  above  that  standard,  apart  from  any  question  of  first  cost, 
the  greater  will  be  the  interference  with  travel  across  the  river, 
up  to  the  point  of  prohibitive  grades  on  the  bridges  and  their 
approaches.  Before  this  point  is  reached  draw  bridges  must  be 
considered  which  while  often  required  and  adopted  are  objection- 
able to  the  interests  using  the  bridges  and  those  passing  under 
'Or  through  the  bridges. 

From  the  view  point  of  the  river  interests  the  most  com- 
plete improvement  would  be  to  do  away  with  the  bridges  entirely, 
thus  giving  absolute  freedom  of  navigation.  This  is  out  of  the 
•question.  The  next  best  thing  from  that  point  of  view  would  be 
to  change  the  bridges  to  one  span  each  across  the  river  from  bank 
to  bank  with  height  enough  for  passage  beneath  of  the  highest 
floating  structures  at  all  stages  of  the  river.  This  would  be  im- 
practicable without  remodeling  the  city  along  both  sides  of  the 
river  for  long  distances  from  the  banks  at  an  expense  so  great 
as  to  be  almost  beyond  computation.  Anything  less  than  this 
will  impose,  at  least  in  theory,  some  hindrance  upon  river  navi- 
gation, and  this  hindrance  will  be  greater  in  amount  as  the  head 
room  is  decreased  and  as  piers  are  introduced  into  the  river. 

The  aim  in  arriving  at  a  solution  of  the  bridge  problem  must 
be  to  adjust  these  conflicting  interests  impartially;  and  the  fac- 
tors to  be  considered  in  arriving  at  such  an  adjustment  are  these: 
First,  the  amount  and  importance  of  the  traffic  likely  to  be  af- 
fected in  each  case.  Second,  the  extent  to  which  any  given  so- 
lution would  benefit  or  injure  the  bridge  traffic  and  the  river 
traffic,  respectively. 

I.     Amount  and  Importance  of  Traffic  Affected. 
Bridge  Traffic. 

There  are  in  question  six  highway  bridges  and  two  railroad 
bridges. 

Before  referring  to  the  statistics  in  regard  to  traffic  over 
these  bridges  we  wish  to  point  out  that  much  the  greater  part 
of  it  is  of  a  kind  daily  and  intimately  affecting  the  business  and 
the  convenience  of  a  large  population.  Any  delay  affecting  the 
transportation  of  passengers  over  any  of  these  bridges,  and  any 
delay  or  any  increase  of  cost  in  teaming  package  freight  and 
supplies  from  freight  stations  and  warehouses  and  stores  on  one 
side  of  the  river  to  their  destination  on  the  other  side,  would  be 
felt  very  sharply  by  a  considerable  fraction  of  the  manufacturers, 


G> 


10 


merchants  and  other  citizens  of  Pittsburgh.  The  inconvenience 
.arising  from  any  interference  with  traffic  of  this  class  would 
clearly  be  greater  in  proportion  to  the  volume  and  value  of  the 
traffic  than  in  the  case  of  the  slower  moving  river  traffic.  Ten 
minutes  delay  to  people  in  reaching  their  offices  or  an  hour's 
delay  beyond  the  expected  time  in  the  delivering  of  household 
food  supplies  or  express  packages,  etc.,  for  a  number  of  fam- 
ilies, is  a  much  more  serious  matter  than  a  corresponding  or  even 
,a  considerably  greater  delay  in  the  delivery  of  a  bargeload  of 
gravel  or  coal,  even  though  the  bargeload  were  of  equal  value 
with  the  delayed  lot  of  supplies. 

Details  in  regard  to  the  volume  of  traffic  over  the  bridges 
and  estimates  of  the  value  of  the  goods  transported  and  the  equip- 
ment engaged  in  the  traffic  are  given  in  Appendix  I  and  are  sum- 
marized in  graphical  form  in  Diagrams  i,  2  and  3.  The  amount 
and  importance  of  bridge  traffic  may  be  summarized  by  stating 
that  there  passes  over  the  existing  Allegheny  river  bridges  each 
year  about  108,000,000  tons  of  traffic  roughly  valued  at  $9,350,- 
000,000;  about  62,700,000  human  beings,  passengers  and  pedes- 
trians. 

River  Traffic. 

The  data  in  regard  to  existing  navigation  under  the  Alle- 
gheny bridges  consists  of  detailed  reports  of  vessels  and  cargoes 
passing  Dam  No.  I  and  counts  of  the  number  of  vessels  passing 
under  the  several  bridges  during  representative  periods  of  from 
one  to  two  months  in  1909.  From  these  data  we  have  estimated 
the  annual  river  traffic  under  each  of  the  bridges,  and  very  rough- 
ly, its  value.*  These  amounts  are  shown  graphically  in  compari- 
son with  the  corresponding  figures  for  traffic  over  the  bridges 
in  Diagrams  I,  2  and  3.  To  briefly  summarize  it  may  be  stated 
that  the  river  traffic  of  the  Allegheny  river  in  one  year  amounts 
in  the  aggregate  to  about  3,500,000  tons,  including  all  freight, 
carriers  and  power  boats  roughly  valued  at  about  $105,000,000 
and  about  35,000  human  beings,  passengers  by  boat. 

It  seems  well  here  to  note  that  the  water  borne  traffic  of 
the  Allegheny  river  has  been  steadily  decreasing  for  many  years 
and  is  now  but  a  small  portion  of  that  which  once  existed.  That 
this  decline  in  river  traffic  is  not  due  to  the  interference  of  the 

*  Appendix  II. 

11 


COMPARATIVE  DIAGRAM  SHOWING 
TOTAL  TONNAGE  OVER  AND  UNDER 
THE  ALLEGHENY  RIVER  BRIDGES. 


TO   ACCOMPANY   REPORT  Of 
COL.  THOMA»  W.  3YMONS. 
FREDERICK  I. AW  OLMSTBO. 


COMPARATIVE  DIAGRAM  SHOWING 
TOTAL  VALUE  OF  TRAFFIC  OVER 
AND  UNDER  THE  ALLEGHENY  RIVER 
BRIDGES. 


TO  ACCOMPANY  REPORT  OF 

rOJ-  THOMAS  W.  SVMONS. 
FKr.Dt.RICK   LAW  OLMVrr.D. 


N0.3. 


13 


bridges  is  shown  by  the  statement  that  the  navigation  facilities 
are  better  than  ever  before,  but  is  due  to  the  lack  of  modern  ter- 
minal facilities,  boats  and  methods  of  carrying  on  business. 

There  is  a  possibility  that  in  case  improved  conditions  are 
provided  for  Allegheny  river  navigation,  the  amount  thereof 
may  increase  with  the  lapse  of  years,  but  for  the  reasons  set  forth 
in  Appendix  II,  this  increase  is  not  likely  to  be  so  great  in  re- 
lation to  the  natural  increase  of  the  bridge  traffic  as  to  render 
the  comparison  of  the  existing  facts  in  Diagrams  i,  2  and  3  in- 
applicable to  the  future. 

Comparison  of  Bridge  and  Eiver  Traffic. 

To  sum  up,  it  may  be  said  that  each  year  the  amount  of 
traffic  passing  over  the  bridges  is  at  least  30  times  that  floating 
on  the  water  of  the  river,  and  about  90  times  its  value.  The 
passenger  traffic  over  the  bridges  is  about  1800  times  that  on  the 
water.  The  character  of  the  traffic  over  the  bridges  is  such  that 
a  given  degree  of  interference  with  it  is  a  far  more  serious  an- 
noyance to  the  public  than  the  same  degree  of  interference  with 
river  traffic. 

II.     Effect  of  Various  Solutions. 

It  remains  to  be  considered  to  what  degree  the  bridge  traffic 
and  the  river  traffic  would  be  hampered  or  facilitated  by  various 
permanent  solutions  of  the  bridge  problem.  With  a  view  to  ar- 
riving at  a  plan  as  nearly  ideal  as  the  circumstances  permit  for 
a  permanent  arrangement  of  bridges  over  the  Allegheny  river, 
various  projects  have  been  put  forward  and  considered.  These 
concern  two  nearly  independent  matters,  the  elevation  of  the 
bridges  above  pool  level  and  the  location  and  design  of  the  bridge 
piers.  The  former  must  be  decided  with  regard  to  the  effect 
upon  both  bridge  and  river  traffic;  the  latter  may  be  determined 
with  regard  solely  to  the  navigation  interests,  giving  due  consid- 
eration to  the  cost  and  the  appearance  of  the  resulting  bridges, 
as  discussed  below. 

The  plan  upon  which  interest  is  now  most  centered  is  that 
officially  recommended  by  the  local  office  of  the  United  States 
Engineer  Corps.  We  shall  consider  the  effect  of  the  bridge 
heights  proposed  in  this  plan  as  compared  with  certain  modifica- 
tions thereof.  First,  upon  the  bridge  traffic,  and  second,  upon 
the  river  traffic. 

14 


Wharf  at  Cologne,  Showing  Heights  of  Boats. 


Paris  Passenger  and  Freight  Boats. 


Effect  of  Various  Possible  Bridge  Heights  upon  the  Traffic 
over  the  Bridges. 
Highway  Bridges. 

The  highway  bridges  carry  two  principal  classes  of 
travel.  The  first  consists  of  vehicles  moved  by  power,  electric 
cars  and  automobiles  and  of  pedestrians.  With  this  class  an 
increase  of  gradient  on  the  bridges  or  their  approaches,  within 
reasonable  limits,  simply  means  the  expenditure  of  a  moderate 
amount  of  additional  energy  without  material  loss  of  time,  or 
other  difficulties.  The  second  class  consists  of  horse  drawn  ve- 
hicles, a  large  portion  of  which  do  not  enter  the  hill  districts,  but 
are  limited  in  their  movements  to  the  large  district  lying  on  the 
lowlands  of  the  three  river  valleys  or  accessible  therefrom  on 
moderate  grades.  A  great  deal  of  this  teaming  consists  of  freight 
of  all  kinds  received  or  shipped  at  the  numerous  freight  stations 
on  both  sides  of  the  river.  The  area  accessible  on  roads  of  easy 
gradient  from  each  end  of  these  bridges  is  very  great  and  in- 
cludes nearly  all  the  important  industrial  plants  in  Pittsburgh  as 
well  as  all  the  freight  stations  and  the  principal  warehouses,  re- 
tail stores  and  other  commercial  establishments  of  Pittsburgh 
and  Allegheny.  Any  considerable  increase  of  grade  on  these 
bridges  means  a  reduction  in  average  size  of  load  hauled  by  ve- 
hicles of  this  important  class,  and  a  corresponding  increase  in 
the  number  of  trips  and  in  the  number  of  teams  required  to  do 
the  work,  making  for  increased  cost  and  greater  congestion  of 
traffic.  For  all  horse  drawn  vehicles  an  increase  of  grade  on  the 
bridges  beyond  a  certain  limit  means,  especially  in  wet  or  snowy 
or  frosty  weather,  more  slipping  and  falling,  more  stalling  of  all 
bridge  traffic  by  such  accidents  and  more  wear  and  tear  on  horse 
flesh,  and  a  resultant  increased  burden  on  the  people.  To  raise 
the  gradient  of  the  bridges  from  those  now  existing  to  those 
indicated  in  the  plans  of  the  local  U.  S.  Engineers'  office  would 
more  than  double  the  traction  effort  required  in  hauling  over 
these  bridges. 

It  must  be  borne  in  mind  that  as  the  grades  increase  the  cost 
of  teaming  and  the  wear  and  tear  on  teams  increase  much  more 
rapidly  than  the  theoretical  effective  horse  power,  because  of  the 
increased  difficulty  of  foothold,  and  with  this  difficulty  of  secur- 
ing good  foothold  the  delays  due  to  the  slipping  and  occasional 
falling  of  horses  also  increase.  It  is  impossible  to  measure  the 

15 


effect  of  any  given  increase  of  grade  with  precision,  but  a  com 
parison  of  the  existing  conditions    with    those    resulting    from* 
various  possible  bridge  heights  will  give  a  good  general  idea  of 
the  effect  as  shown  by  the  following  tables : 


TABLE  SHOWING  BRIDGE  GRADES 

INVOLVED  BY  THE  ADOPTION  OP  VARIOUS 

CLEARANCE  HEIGHTS. 

euevATioN  AOOVC 

POOL  LEVEL    Of 
UNDER  SIDE    Or 

PRBCNT 

37 

v 
42 

^7 

pRtttm 

^7 

42 

47 

BRID6*      OVCA 

36O'   CHANNEL. 

**  MAXIMUM  GRADED 

AMOUNT  OP  Ri^t  in  rter 

ABOVE  PuQUC5He  WAY. 

6m  ST.  epioee. 

2.r/0± 

3.2% 

45% 

• 

^.8^ 

/.5 

10.4 

13.4 

2a4 

7TW.5T    6R»Dflt 

aoK* 

3.7  '/« 

'*% 

<*3% 

10.0 

14,2 

19.2 

24.2 

9TH  ST.  epiooe 

ti&A 

33% 

r/o 

*>•>% 

io.r 

/3.3 

/8.5 

23.3 

*Grades  for  this  clearance  height  are  greater  than  those 
shown  on  U.  S.  Engineers'  plans  because  of  greater  width  of 
channel.  If  U.  S.  Engineers'  plans  were  adopted  the  maximum 
grades  would  be  as  follows:  Sixth  street,  4.35%;  Seventh  street, 
4.93%,  and  Ninth  street,  4.98%. 

**The  maimum  grades  here  given  assume  the  above  men- 
tioned improvement  of  the  short  pitches  now  existing  on  some^ 
of  the  bridge  approaches. 


Barge  and  Tow  Boat  Designed  for  Shallow  Rivers  and  Low  Bridges 
in  the  United  States. 


TABLE  SHOWING  EFFECTIVE  ENERGY 
REQUIRED  TO  OVERCOME  RISE  OVER 
BRIDGES  AT  VARIOUS  HEIGHTS. 

ELEVATION  ABOVE 
POOL  UEVE  L  OP 
UNDER  SIDE  OF- 
BRIDGE     OVfcR 
36o'  CHANNEL. 

PRE5CNT. 

3/. 

4.2. 

^7 

TONSPCRANrtUN 

TOOT   TONS  Of*  CPPCCTIVe    CMCCGY 

6TH5T.  BR. 

13.240.010 

99,500/3^5 

137.696.104 

Z03.896I54 

270,09^204 

9TH.5T  BR. 

[4.732.l?0 

I5».740,9?9 

I95.937.3Z9 

269,597979 

343.258,4>Z9 

PERCENT    OT-     INCREASE    OP  CPrtCTlVE 
ENERGY  REQUIRED 

6TH.5I  BRIOGt 

36.6% 

ro*>.3°/£ 

172.0% 

9THST  dRfDGE 

29.1% 

777% 

126.2% 

At  the  Sixth  street  bridge  there  is  at  present  an  undesirably 
steep  grade*  on  the  Allegheny  or  Northside  approach,  but  it  is 
only  230  feet  long  and  being  paved  with  stone  gives  a  good  foot- 
hold for  horses.  This  is  to  be  greatly  benefited  by  filling  up  the 
street  with  material  taken  from  the  "Hump"  grading ;  the  plans 
on  file  in  the  City  Bureau  of  Construction  providing  for  an  im- 
proved grade  of  only  2.22  per  cent.  Many  of  the  abutters  have 
already  waived  their  damages  and  there  is  no  question  that  the 
improvement  will  be  made. 

The  present  bridge  grades  and  those  of  the  Pittsburgh  ap- 
proach are  less  than  3  per  cent.  At  the  Seventh  street  bridge 
the  grades  do  not  exceed  3  per  cent.,  except  on  the  Allegheny 
approach  where  the  grade  is  now  being  improved  so  as  to  reduce 
it  to  2  per  cent.  At  Ninth  street,  while  the  present  bridge  grades 

*3.64  per  cent.  (United  States  Engineers'  Office)  or  4.0 
per  cent.  (City  Bureau  of  Construction.) 

17 


do  not  exceed  2.8  per  cent.,  there  is  a  short  pitch  about  100  feet 
long  in  the  approach  on  the  Allegheny  side  with  a  grade  of  5.24 
per  cent.**  A  small  amount  of  regrading,  involving  no  heavy 
property  damages  will  suffice  to  reduce  these  grades  to  1.3  per 
cent.,  and  appropriations  for  this  improvement  have  already  been 
made  by  the  city. 

The  existing  grades  at  the  Sixteenth  street,  Thirtieth  street 
and  Forty-third  street  bridges  are  light,  but  it  is  not  important 
to  consider  these  bridges  in  detail  in  this  connection  as  it  is  prob- 
able that  the  necessity  for  eliminating  railroad  grade  crossings 
will  sooner  or  later  alter  the  existing  approaches  in  such  a  man- 
ner that  the  resulting  grades  would  not  be  further  increased  by 
raising  the  bridges.  It  is  to  be  noted,  however,  that  the  precise 
elevations  recommended  by  the  local  office  of  the  U.  S.  Engineers 
for  these  bridges  would  involve  serious  complications  with  the 
railroad  tracks. 

In  many  cities  having  similarly  situated  level  business  and 
manufacturing  districts  along  rivers,  very  large  sums  of  money 
have  been  spent  to  reduce  the  grades  on  the  connecting  bridges 
to  less  than  3  per  cent.,  and  that  figure  is  rather  generally  regard- 
ed by  engineers  as  a  maximum  upon  important  traffic  bridges. 

People  in  Pittsburgh  are  so  accustomed  to  steep  grades  in 
the  adjacent  hill  districts  that  they  are  apt  to  ignore  the  fact  that 
their  is  a  city  within  their  city,  and  that  this  inner  manufacturing 
and  business  city  is  closely  confined  to  the  long  drawn-out  irre- 
gular, level  river  bottoms  and  is  much  freer  from  hills  than  New 
York,  almost  as  much  as  Chicago. 

The  city  has  expressed  its  willingness  to  spend  a  large  sum 
of  money  and  undergo  great  inconvenience  for  the  sake  of  a 
moderate  reduction  in  the  street  grades  of  the  "Hump"  at  one  of 
the  gateways  of  the  hiil  districts.  Important  as  this  work  is, 
it  cannot  be  compared  for  a  moment  as  a  matter  of  traffic  im- 
provement with  the  importance  attaching  to  easy  grades  on  the 
bridges,  for  the  streets  of  the  "Hump"  district  lead  in  the  main 
from  the  flat  part  of  the  city  to  the  hilly  part  where  average 
loads  are  limited  by  the  prevailing  steep  grades,  whereas  the 
bridges  lie  between  two  parts  of  the  level  industrial  and  com- 
mercial city.  If  at  low  grades  they  serve  to  unite  them;  if  at 
high  grades  they  divide  them. 

**Given  as  6.35  per  cent,  on  U.  S.  Engineers*  Sections. 

18 


Railroad  Bridges. 

In  so  far  as  any  changes  in  the  railroad  bridges  produce 
conditions  less  convenient  and  expeditious  for  handling  the  busi- 
ness which  the  people  have  to  do  with  the  railroad  the  public  has 
a  direct  concern  in  the  matter. 

With  regard  to  the  Junction  Railroad  bridge  of  tke  Balti- 
more and  Ohio  Railroad  System,  the  raising  proposed  by  the  local 
office  of  the  U.  S.  Engineers,  appears  to  involve  no  serious  dif- 
ficulties in  operation  which  would  affect  the  general  public  or  the 
shippers. 

With  regard  to  the  Pittsburgh,  Fort  Wayne  and  Chkago 
bridge  of  the  Pennsylvania  System,  it  is  to  be  noted  that  this 
is  a  double  deck  bridge,  the  upper  tracks  being  used  principally 
by  passenger  trains  and  the  lower  tracks  by  freight  trains  almost 
exclusively  devoted  to  local  freight  business.  The  most  serious 
consideration  affecting  this  bridge  is  that  any  very  considerable 
raising  of  the  level  of  the  lower  tracks  would  throw  them  out 
of  connection  with  the  important  local  freight  station  to  which 
those  tracks  run.  Even  if  expense  of  reconstruction  be  wholly 
disregarded  we  believe  no  way  can  be  devised  by  which  the 
freight  tracks  of  the  Fort  Wayne  bridge,  if  raised  as  proposed 
by  the  local  office  of  the  U.  S.  Engineers  can  be  connected  with 
the  freight  station  and  industrial  plants  without  involving  greatly 
increased  difficulty  and  delay  in  the  handling  of  freight  either 
on  the  tracks  or  in  the  station  itself  or  in  the  teaming  approaches 
to  the  station.  When  the  large  volume  of  local  traffic  handled 
at  this  station  is  considered,  it  is  apparent  that  such  a  radical 
change  is  a  serious  matter  for  shippers  and  the  great  manufac- 
turing and  commercial  industries  of  the  city.  Other  than  the 
expense  of  making  changes  in  the  bridge  and  its  approaches  no 
serious  difficulty  stands  in  the  way  of  raising  the  clearance  of  the 
main  span  of  the  Fort  Wayne  bridge  2  or  3  feet  to  about  37 
feet  above  pool  level.  To  go  above  that  figure  involves  the  ser- 
ious objections  discussed  above. 

Effect  of  Different  Bridge  Heights  Upon  River  Traffic. 

The  effect  upon  river  navigation  of  any  standard  that  may 
be  adopted  for  the  heights  of  bridges  depends  upon  the  heights 
of  the  vessels  using  the  river  and  the  fluctuations  of  the  river 
level  itself.  See  Diagrams  4  and  5. 

19 


By  means  of  Davis  Island  Dam  in  the  Ohio  river  the  water 
of  Pittsburgh  harbor  is  now  kept  practically  at  a  minimum  stage 
of  6  feet  above  the  datum  of  zero  at  natural  low  water.  This 
is  the  prevailing  water  level  for  the  greater  portion  of  the  year. 
Floods  come  occasionally  produced  by  rains  and  melting  snows 
and,  of  course,  with  the  floods  come  increased  current  velocities. 
These  current  velocities  of  each  river  depend  upon  the  source  of 


the  flood.  When  the  flood  comes  down  the  Allegheny  river  high 
velocities  result.  When  the  flood  comes  down  the  Monongahela 
the  high  water  in  the  Allegheny  is  back-water  without  excessive 
currents.  Under  this  condition  the  Allegheny  becomes  a  harbor 
of  refuge  for  Monongahela  commerce;  and  the  reverse  is  true 
that  in  an  Allegheny  river  flood  the  Monongahela  becomes  a  har- 
bor of  refuge  for  Allegheny  commerce.  The  floods  in  the  two 
rivers  seldom  come  at  the  same  time  on  account  of  the  differences 
in  the  topography  and  climatic  conditions  along  the  two  water 
sheds.  The  most  serious  floods  in  the  Allegheny  generally  come 
in  the  spring  when  they  are  frequently  accompanied  with  drift 
and  ice  to  such  an  extent  as  to  render  navigation  dangerous.  At 
a  stage  of  15  feet  in  an  Allegheny  river  flood  the  river  current 
runs  at  rates  of  from  4  to  7  miles  per  hour.  The  record  of  fifty 
five  years  shows  that  there  is  an  average  of  9  days  each  year 
when  the  river  is  above  a  15  foot  stage  and  this  is  mostly  in  the 
winter  and  spring  when  navigation  in  the  harbor  is  at  its  lowest 
ebb.  There  is  presented  herewith  Diagram  IV  showing  graphi- 
cally the  average  number  of  days  each  year  during  which  the 
river  has  reached  the  various  heights  indicated. 

There  is  also  presented  a  hydrograph  record  of  the  river 
for  4  years  past  which  indicates  the  conditions  ordinarily  met 
with  as  regards  river  stages  at  various  times  of  year. 

In  the  balancing  of  interests  between  the  traffic  on  the  river 
and  that  across  the  bridges,  it  is  believed  to  be  fair  and  just  that 
for  boats  of  excessive  size  and  height  the  navigation  of  the  river 
above  a  15  foot  stage  be  eliminated  from  the  problem;  (i)  be- 
cause of  the  comparatively  small  number  of  these* boats;  (2) 
because  of  the  questionable  necessity  of  having  such  high  boats 
at  all;  (3)  because  of  the  period  of  the  year  when  these  extreme 
stages  are  reached;  (4)  because  these  periods  of  time  are  so  lim- 
ited in  length;  (5  because  of  the  generally  accompanying  swift 
currents,  and  (6)  because  of  the  ofttimes  accompanying  danger- 
ous floating  drift  and  floating  ice. 

As  to  the  height  of  vessels,  it  is  to  be  noted  that  the  great 
bulk  of  navigation  under  the  bridges  is  not  through  traffic,  but 
is  simply  movements  about  in  the  lower  stretch  of  the  river  which 
forms  part  of  the  harbor  of  Pittsburgh.  The  commodities  moved 
are  nearly  all  sand,  gravel  and  coal  in  barges,  which  loads  are 
almost  invariably  taken  up  stream  while  the  downward  movement 
is  mostly  of  empty  barges.  These  barges  are  mostly  moved  by 
harbor  tugs.  The  harbor  tugs  actually  in  use  are  from  22  to 
27  feet  high,  averaging  about  24  feet. 

21 


The  heights  of  the  Monongahela  standard  to  wheats  vary 
from  24  to  32  feet,  averaging  about  28  feet.  Out  of  a  list  of  28 
such  boats  but  5  exceed  28  feet  in  height. 

The  few  packet  boats  running  on  the  river  are  of  moderate 
height  and  can  be  accommodated  in  the  harbor  under  the  bridges 
at  ordinary  river  stages.  The  amount  of  business  that  could 
be  done  by  a  few  packet  boats  of  extreme  and  unnecessary  height 
is  so  small  that  to  raise  the  bridges  to  a  sufficient  height  to  ac- 
commodate it  would  place  an  entirely  unjustifiable  tax  and  in- 
convenience upon  the  far  greater  business  interest  of  the  city 
concerned  in  crossing  the  river. 

The  following  tables  show  the  average  number  of  days  per 
annum  during  which  various  types  of  existing  vessels  would  be 
prevented  from  navigation  by  bridges  of  various  assumed  heights 
above  the  Davis  Island  Pool : 


—    TABLE    SHOWING    EFFECT  OF    VARIOUS 
CLEARANCE    HEIGHTS    UNDER    BRIDGES. 

ASSUMED     BRIDGE    HEIGHT 

ABOVE  POOL,  ueveu 

PRESCHT 

&TH.ST.  ee 

33 

37 

42 

^7 

TYPES  Or  VESSELS. 

TOTAL  NO-  OF   DAY*    Pe«    ANNUM  V/HfcN 
CUEARANCC.  WOULD   BE    IMSUPfHCICNT. 

HARBOR  TUGS  AV.  HEIGHT     24* 

It 

3 

\ 

1 

HARBOR  TUGS  MAX.heiGfIT  Zf 

% 

9 

\ 

f 

MONONGAHELA    BOATS                9A< 
ORDINARY  MAX.  HEIGHT.              ^° 

^ 

12 

Z 

1 

MONON6AHELA    BOATS               »2« 
EXTREME    MAX.  HEIGHT 

!?8 

57 

9 

1 

TYPES  OF  VESSELS 

TOTAL    NO-    OF    DAYS   PC<?    AN  HUM  WMCH 
CLEARANCE    WOULD    Bt    IN  JUP^lCl  fe.MT 

CACLUOIMO  DAYS   WHCrf  RtvCA  »i  ACCS% 
15    FOOT  dTAafc 

HARBOR  TU6S  AV  HEIGHT         24* 

3 

0 

o 

o 

HARBOR  TUC5  MAX.  MtieHT.     f]' 

28 

o 

0 

o 

MONOMQAHCtLA     BOATS                  -o« 
OPDlflAPY  MAX.  HC.KSHT.           Z& 

46 

3 

o 

0 

MOiMONftAHfelA     »OAT*                 ~*« 
tXTRtMfc  MAX.  HClflHT.             Jf> 

169 

46 

o 

0 

In  drawing  conclusions  from  the  above  table  as  a  basis  for 
plans  governing  the  expenditure  of  millions  of  dollars  in  con- 
struction and  the  permanent  establishment  of  conditions  of  navi- 
gation and  of  traffic  over  the  bridges  and  the  enormous  business 
interests  concerned,  it  is  important  to  bear  in  mind  that  the  types 
of  vessels  here  considered  are  antiquated,  and  can  undoubtedly 
be  materially  changed  in  many  particulars  to  the  benefit  of  all 
interests. 

As  bearing  directly  on  this  question  of  boats  and  bridges 
attention  is  invited  to  the  following  extract  from  the  report  of 
Hon.  D.  S.  Alexander,  Chairman  of  the  River  and  Harbor  Com- 
mittee of  the  U.  S.  House  of  Representatives,  in  submitting  for 
action  of  the  House  the  last  river  and  harbor  bill  February  nth, 
1910: 

Modern  Type  of  Boats  for  Nontidal  Rivers. 

"The  British  Government  has  been  designing  shallow- 
draft  boats  for  use  on  the  Nile,  and  the  German  and  Austrian 
governments  have  been  working  along  similar  lines  with 
reference  to  methods  of  transportation  on  the  Rhine,  the 
Danube,  the  Elbe  and  other  waterways.  The  boats  designed 
have  been  very  successful,  having  been  used  in  connection 
with  modern  loading  and  unloading  appliances.  On  our 
western  rivers  little  change  has  been  made  in  the  design  of 
towboats,  barges,  etc.,  since  1860,  and  it  is  believed  that  a 
design  embodying  the  best  points  of  modern  vessels,  with 
modern  machinery  and  cargo  handling  devices,  might  lead 
to  a  marked  increase  in  the  traffic  on  the  nontidal  rivers  of 
the  United  States,  especially  after  permanently  improved 
channels  are  available. 

"It  is  believed  that  the  appropriation  of  $500,000  to  be 
expended  in  the  purchase  of  plant  for  use  in  connection  with 
the  work  of  improvement  of  the  river  will  also  provide  for 
experiments  to  be  carried  on  by  the  Government  which  will 
result  in  improving  the  present  type  of  river  freight  carriers, 
and  also  that  these  tests  can  be  made  in  no  other  wayL since 
the  expenditures  and  uncertainties  involved  preclude  the  use 
of  private  capital  for  the  purpose.  As  a  result  of  the  tests 
or  experiments  it  is  hoped  that  a  large  saving  to  the  country 
at  large  may  accrue  from  decreased  costs  of  transportation, 
and  that  a  type  of  carrier  may  be  developed  which  will  also 
reduce  the  cost  of  all  bridges  across  navigable  streams  due 
to  lessened  requirements  in  the  matter  of  head  room." 

This  report  of  Col.  Alexander,  the  very  able  Chairman  of 
the  River  and  Harbor  Committee  of  the  House  of  Representa- 

23 


tives,  is  worthy  of  serious  consideration.  Such  an  investigation 
and  experiments  to  determine  the  best  type  of  carriers  to  use  on 
the  river  seems  certain  to  be  provided  for  and  may  result  in 
clearly  demonstrating  that  no  necessity  exists  for  raising  the  Al- 
legheny bridges  at  all,  in  accordance  with  the  possibility  outlined 
by  the  closing  paragraph  of  Col.  Alexander's  report  above.  The 
appropriation  of  $500,000  as  recommended  by  Col.  Alexander 
is  included  in  the  river  and  harbor  bill  which  has  passed  the 
House  qf  Representatives  and  Senate.  There  is  every  proba- 
bility that  it  will  become  a  law. 

A  vast  amount  of  water  traffic  is  carried  on  inland  waterways 
all  over  the  world  under  fixed  bridges  with  far  less  head  room 
than  is  provided  for  under  the  Allegheny  river  bridges.  It  is 
customary  in  other  parts  of  the  country  and  the  world  to  estab- 
lish for  rivers  a  minimum  head  room  for  bridges  at  a  high  naviga- 
ble stage,  which  stage  is  considerably  lower  than  the  maximum 
or  even  the  ordinary  high  flood  stage.  For  instance,  in  the  new 
barge  canal  being  built  by  the  State  of  New  York  at  a  cost  of 
$108,000,000  the  minimum  head  room  under  all  stationary  bridges 
is  fixed  at  15  1-2  feet  at  the  high  navigable  stage  of  the  water. 
The  high  navigable  stage  is  based  chiefly  upon  what  is  a  safe 
navigable  stage  taking  everything  into  consideration.  It  is  by 
no  means  a  very  high  stage.  As  this  canal  runs  through  the 
canalized  Mohawk,  Oneida,  Oswego,  Seneca  and  Clyde  rivers 
the  situation  is  comparable  with  that  on  the  Allegheny.  The 
depth  of  the  canal  at  low  water  is  to  be  12  feet,  so  it  is  seen  that 
the  clear  head  room  is  but  about  25  per  cent,  greater  than  the 
minimum  depth  of  the  water.  The  boats  must  be  made  to  fit 
the  bridges,  and  not  the  bridges  to  fit  the  boats.  It  is  estimated 
that  the  amount  of  traffic  which  will  pass  through  these  canals 
about  450  miles  long  and  under  these  15  1-2  foot  bridges  will  be 
about  20,000,000  tons  annually,  many  times  the  amount  making 
use  of  the  Allegheny  river.  The  present  Erie,  Champlain  and 
Oswego  canals  in  the  State  of  New  York  which  have  been  in 
operation  for  about  80  years,  are  crossed  by  several  hundred 
bridges  giving  a  clear  head  room  of  13  feet.  No  complaint 
about  this  head  room  is  known  to  exist,  notwithstanding  that 
steam  vessels  are  largely  used  for  navigation  purposes  on  the 
canals.  The  boats  have  to  be  made  to  fit  the  bridges  and  not 
the  bridges  to  fit  the  boats. 

24 


C3 


At  Paris,  France,  the  river  Seine  running  through  the  city 
carries  a  very  large  amount  of  business.  Annually  about  20,000,- 
ooo  passengers,  and  about  11,000,000  tons  of  freight  are  carried 
on  boats  of  various  kinds.  There  are  36  bridges  which  span  the 
river  and  must  be  passed  by  the  water  borne  traffic.  The  clear 
head  room  under  these  bridges  at  the  highest  navigable  water 
varies  from  11.25  feet  to  21.88  feet.  By  highest  navigable  water 
is  meant  the  stage  of  water  when  by  reason  of  floods  or  currents, 
navigation  ceases.  This  Paris  water  borne  freight  traffic  on  the 
Seine  amounts  to  fully  7  times  that  of  the  Allegheny  river  and 
passes  under  5  times  as  many  bridges,  with  minimum  available 
head  room  at  high  navigable  stages  just  about  one  half  that  under 
the  present  bridges  over  the  Allegheny  at  a  15  foot  stage.  The 
conditions  of  navigation  on  the  Seine  at  Paris  are  practically 
the  same  as  those  on  the  Allegheny  at  Pittsburgh.  In  Paris  the 
boats  are  made  to  fit  the  bridges  and  not  the  bridges  to  fit  the 
boats. 

From  these  and  many  other  illustrations  that  could  be  given 
it  is  evident  that  it  is  not  universally  or  even  commonly  consid- 
ered necessary  or  advisable  to  sacrifice  business  interests  cross- 
ing the  bridges  to  navigation  interests  using  the  waterways,  to 
any  such  extent  as  that  demanded  by  the  navigation  interests  of 
the  Allegheny  river. 

Conclusions  as  to  Clearance  Heights. 

Disregarding  for  the  moment  the  question  of  the  time  when 
changes  in  the  present  bridges  should  be  required,  it  is  believed, 
after  very  careful  consideration,  that  the  conditions  brought  out 
by  our  study  of  the  problem  would  best  be  met  by  fixing  the  ele- 
vation for  a  substantial  portion  of  each  bridge  in  the  center  at  a 
clear  height  above  the  pool  level  of  substantially  37  feet,  or  28 
feet  above  the  river  at  a  15  foot  stage  at  each  bridge.  It  is  be- 
lieved that  this  elevation  will  give  fair,  justifiable  and  all  really 
needed  accommodations  to  the  navigation  interests.  This  height 
can  be  attained  without  extravagant  and  unjustifiable  expense 
and  inconvenience  to  the  business  interests  involved  in  crossing 
the  river,  and  while  it  cannot  be  hoped  that  it  would  be  satisfac- 
tory to  the  extreme  advocates  of  river  and  harbor  interests,  it 
ought  to  satisfy  those  who  are  able  and  willing  to  give  proper  and 
fair  consideration  to  other  interests  than  their  own.  There  are  no 
reasonable  navigation  demands,  with  bridges  at  this  elevation, 

25 


that  cannot  be  met  if  the  water  borne  commerce  be  conducted 
with  vessels  of  the  best  modern  accepted  type  and  not  of  ex- 
treme or  unnecessary  height. 

Piers  and  Channels. 

0 

For  the  benefit  of  the  navigation  interests  there  are  certain 
changes  in  some  of  the  bridges  over  the  Allegheny  that  should 
be  made  without  question.  These  relate  to  the  location  of  piers 
and  location  and  width  of  the  navigable  channels. 

At  the  mouth  of  the  Allegheny  river  a  new  bridge,  the 
Northside  Point  bridge,  has  been  approved  by  the  War  Depart- 
ment and  is  to  be  built  at  the  extreme  mouth  of  the  river.  This 
is  to  have  one  central  pier  dividing  the  river  into  two  channels. 

A  short  distance  above  this  Northside  Point  bridge  is  sit- 
uated the  Sixth  street  bridge,  in  some  respects  the  most  impor- 
tant highway  structure  crossing  the  river.  This  bridge  now  cor- 
responds to  the  Northside  Point  bridge  in  having  a  central  pier 
and  dividing  the  river  into  two  main  channels  of  ample  width 
of  over  400  feet. 

The  next  bridge,  the  Seventh  street  bridge,  also  has  now  a 
central  pier  with  channels  about  320  feet  wide  on  each  side  of 
it. 

The  next  bridge  up  the  river,  that  at  Ninth  street,  has  shor- 
ter spans  with  the  piers  so  unfortunately  located  as  to  be  de- 
cidedly obstructive.  As  this  bridge  is  of  relatively  light  con- 
struction it  is  possible  that  the  heavy  and  constantly  increasing 
traffic  which  it  is  called  upon  to  bear  will  before  long  necessitate 
its  reconstruction  anyway,  and  it  will  not  be  unreasonable  to 
require  it  to  be  rebuilt  with  fewer  piers  properly  located  to  con- 
form to  the  plan  adopted  for  the  Sixth  street  and  Seventh  street 
bridges. 

As  a  permanent  arrangement  of  piers  for  the  above  three 
bridges  either  of  two  logical  plans  may  be  adopted.  The  first  is 
to  retain  the  existing  two-spans  center-pier  arrangement  of  the 
Sixth  street  and  Seventh  street  bridges,  conforming  to  the  center 
pier  plan  required  by  the  U.  S.  Engineers  for  the  new  Northside 
Point  bridge,  and  reconstruct  the  Ninth  street  bridge  upon  the 
same  general  plan.  The  other  is  to  reconstruct  all  three  bridges 
with  two  piers  and  three  spans  each,  as  recommended  by  the 
local  office  of  the  U.  S.  Engineers.  The  first  or  central  pier 
plan  has  the  merit  of  economy  of  construction  in  that  it  involves 

26 


Tow  Boat  and  Barge  Passing  Under  Low  Bridge. 


Closer  View  of  Such  Tow  Boat  and  Barge. 


the  construction  of  no  new  piers  for  the  Sixth  street  and  Sev- 
enth street  bridges,  and  permits  the  continued  use  of  the  exist- 
ing superstructures  of  the  Sixth  street  and  Seventh  street 
bridges  by  simply  raising  them  to  the  elevation  that  may  be  de- 
cided upon  and  ordered.  So  far  as  we  can  ascertain,  in  view  of 
the  center  pier  plan  adopted  for  the  Northside  Point  bridge,  the 
advantage  to  navigation  appears  to  lie  on  the  side  of  adhering 
to  a  center  pier  plan  for  these  bridges  also.  On  the  other  hand, 
there  is  no  doubt  that  three  span  bridges  could  be  made  more 
agreeable  in  appearance  than  two  span  bridges.  But  the  pos- 
sible gain  in  appearance  alone  does  not  appear  sufficient  to  jus- 
tify the  adoption  of  three  spans. 

The  next  bridge  above  Ninth  street  is  that  of  the  Pitts- 
burgh, Fort  Wayne  and  Chicago  Railroad.  This  has  been 
constructed  with  two  main  piers  providing  one  main  central 
channel  337.5  feet  wide  and  three  other  piers  giving  four 
channels  from  155  to  163  feet  wide.  Owing  to  the  bend  in 
the  river  at  the  bridge  and  the  distance  above  the  Ninth 
street  bridge  there  is  no  valid  objection  to  this  single  main 
central  channel  at  the  railroad  bridge  connecting  either  with 
two  channels  divided  by  the  central  piers  of  the  bridges  be- 
low or  with  a  central  channel  if  those  bridges  should  be  re- 
constructed on  the  three  span  plan. 

The  Sixteenth  street  bridge  has  been  constructed  with  3  piers 
dividing  the  river  into  4  channels  of  about  150  feet  each;  the 
clear  head  room  beneath  it  is  less  than  that  now  given  by  the 
bridges  below  it.  The  best  arrangement  to  be  made  with  this 
bridge  is  to  require  it  to  be  rebuilt  without  the  central  pier  leav- 
ing a  central  channel  about  320  feet  in  width  between  the  two 
side  piers  to  correspond  with  the  railroad  bridge  just  below  it.  It 
is  an  old  covered  wooden  bridge  in  poor  physical  condition,  and 
as  previously  noted,  it  is  probable  that  it  must  be  raised  anyhow 
in  connection  with  eliminating  railroad  grade  crossings  on  the 
the  approaches. 

The  Thirtieth  street  bridge  has  its  piers  properly  spaced  to 
leave  a  central  channel  285  in  clear  width  and  no  changes  are 
required  in  pier  and  channel  location  at  this  bridge. 

The  Thirty-third  street  or  Pittsburg  Junction  Railroad  bridge 
of  the  Baltimore  and  Ohio  Co.,  has  three  piers  giving  a  main 
central  channel,  of  232  feet  wide,  with  side  channels  195  feet 
wide,  and  on  the  Herrs  Island  side  of  150  feet.  No  change 

27 


is  needed  in  the  location  of  the  piers  and  channels  at  this 
bridge. 

The  Forty-third  street  bridge  is  built  with  three  piers 
making  four  channels  each  of  about  160  feet  wide.  It  gives 
less  clear  head  room  at  high  river  stages  than  most  of  the 
lower  river  bridges.  It  is  an  old  wooden  bridge  in  poor 
physical  condition.  The  best  arrangement  for  this  bridge  is 
to  treat  it  as  the  Sixteenth  street  bridge  and  to  require  it  to 
be  rebuilt  omitting  the  central  pier  and  leaving  a  central  chan- 
nel about  300  feet  wide  to  correspond  with  the  bridges  below 
it.  The  elimination  of  railroad  grade  crossings  on  the  ap- 
proaches to  this  bridge  is  already  a  pressing  public  need  and 
must  soon  result  in  its  raising  or  reconstruction  at  a  higher 
level. 

Considerations  Against  Requiring  Changes  in  Bridges  to  be 
.Made  at  Present 

The  following  important  questions  having  a  direct  bear- 
ing upon  the  proper  design  of  permanent  bridges  across  the 
Allegheny  river  are  now  under  consideration: 

1.  The  Flood  Commission  is  getting  data  for  studying 
the  question  of  a  protective  embankment  along  the  river  front 
and  of  the  proper  grades  of    streets  and  bridge  approaches  in 
the  region  subject  to  inundation     The  design  of  such  flood 
protection  works   should  have  important  bearing  upon  the 
grade,  location  and  design  of  the  permanent  bridge  abutments. 
This  Commission  is  also  studying  the  question  of  impounding 
the  flood  waters  of  the  Allegheny  and  Monongahela  rivers  in 
their  upper  valleys,  which  may  result  in  materially  lessening 
the  height  and  velocity  of  floods  in  the  harbor  of  Pittsburgh, 
and  consequently,  simplify  the  bridge  and  navigation  problems 
of  the  harbor. 

2.  The  question  of  the  best  routes  for  surface  cars  and 
rapid  transit  lines  crossing  the  Allegheny  river  is  now  being 
studied  for  the  city  as  a  part  of  a  comprehensive  plan  for  trac- 
tion improvements.  The  result  of  these  studies  might  readily 
affect  the  design  of  the  new  bridges. 

3.  The  government  experiments  recommended  by  Col. 
Alexander  of  the  River  and  Harbor  Committee  and  author- 
ized in  the  river  and  harbor  bill  just  passed  by  Congress  and 
providing  for  the  development    of   a    more    economical    and 

28 


efficient  type  of  river  boats,  requiring  less  head  room  than  the 
present  antiquated  types,  may  soon  show  results  that  would 
have  a  decided  influence  in  determining  the  reasonable  clear- 
ance heights  of  bridges. 

4.  Attention  is  also  invited  to  the  fact  that  the  people  of 
Pittsburgh  have  voted  to  expend  about  $7,000,000  in  certain 
public  improvements.  Among  these  are  the  cutting  down  of 
the  "Hump",  an  obstructive  hill  in  the  city's  midst,  widening 
some  streets  and  filling  certain  other  streets  in  the  Northside 
and  West  End  that  are  flooded  at  high  river  stages.  The 
material  from  the  "Hump"  in  the  vicinity  of  the  Court  house 
is  to  be  hauled  to  these  Northside  streets  across  the  lower 
Allegheny  bridges  under  question.  The  work  is  of  great 
magnitude  and  it  will  take  at  least  two  years  to  complete 
it.  Any  material  alteration  to  the  bridges  such  as  proposed 
by  the  Board  of  Engineers  will  require  a  long  time  to  be 
carried  into  effect.  While  this  bridge  work  would  be  under 
way,  the  transportation  of  the  material  excavated  from  the 
"Hump"  and  filling  up  the  low  grade  streets  of  the  Northside 
would  have  to  cease  or  would  be  carried  on  with  great  dif- 
ficulty and  inconvenience  to  other  traffic.  This  would  tie  up 
the  whole  work  while  it  is  in  progress,  causing  material  in- 
jury to  the  city,  for  it  is  to  be  extremely  annoying  and  bother- 
some while  it  is  in  progress  and  the  longer  this  period  is 
strung  out  the  worse  it  will  be. 

For  all  of  the  above  reasons  we  believe  that  to  precipi- 
tate the  actual  reconstruction  of  the  bridges  at  this  time  would 
be  most  undesirable  for  the  city  and  prejudicial  to  the  best 
results  in  the  long  run  for  all  concerned. 

RECOMMENDATIONS. 

In  conclusion  we  beg  to  recommend  as  follows : 
I.  That  the  Sixteenth  street  and  Forty-third  street 
bridges  which  are  obstructions  to  navigation  on  account  of 
their  pier  locations,  narrow  channels,  and  exceptionally  low 
clearance  height  be  required  to  be  rebuilt  with  their  piers  so 
located  as  to  give  channels  conforming  to  the  neighboring 
bridges,  and  that  their  elevation  be  fixed  with  regard  to  elimi- 
nating the  railroad  grade  crossings  on  their  approaches,  but 
the  minimum  clearance  shall  be  fixed  in  accordance  with  the 
closing  paragraph  below. 


2.  That  the   Ninth   street  bridge   should  be   rebuilt  as 
soon  as  practicable  with  a  center  pier  and  two  wide  spans  con- 
forming to  those  of  the  Sixth  street  and  Seventh  street  bridges. 
The  design  of  the  new  Ninth  street  bridge,  however,  should  not 
be  finally  determined  and  erection  begun  until  a  definite  plan 
for  comprehensive  improvements  in  the  traction  system  be- 
tween the  two  sides  of  the  river  has  been  decided  upon.   Unless 
new   circumstances   develop   before   the   construction  of  this 
bridge  is  begun  that  materially  affect  the  problem  of  clear- 
ance height,  the  elevation  should  be  fixed  in  accordance  with 
the  closing  paragraph  below. 

3.  That  all  questions  pertaining  to  changing  the  eleva- 
tion of  the  Sixth  street,  Seventh  street,  Fort  Wayne,  Thirti- 
eth street  and  Junction  Railroad  bridges  be  deferred  to  await 
the  report  of  the  Pittsburgh  Flood  Commission  and  the  re- 
sultant action;    to  await  the  report  on  a  comprehensive  plan 
for  traction  improvements;  to  await  the  completion  of  the 
work  projected  by  the  city  in  cutting  down  some  streets  and 
filling  others,  and  to  await  the  results  of  investigation  of  river 
boat  design  and  construction  provided  for  in  the  river  and 
harbor  bill  just  passed  by  Congress. 

4.  That  if  it  is  deemed  essential  and  necessary  at  pre- 
sent to  decide  upon  the  elevation  to  which  all  Allegheny  river 
bridges  must  be  made  to  conform,  this  elevation  be  fixed  so 
that  there  shall  be  a  clear  head  room  of  substantially  37  feet 
above  pool  level,  varied  so  as  to  give  at  each  bridge  a  clear 
head  room  of  28  feet  when  the  river  is  at  a   15  foot  flood 
stage.    This  height  to  be  maintained  over  the  entire  main  span 
where  there  is  a  central  span  and  for  180  feet  on  each  side 
of  the  central  pier  where  there  is  a  central  pier. 

We  have  the  honor  to  be 
Very  respectfully, 

Your  (obedient  servants, 

Thomas  W.   Symons, 

Col.  Corps  Engineers  U.  S.  A.,  retired, 

Frederick   Law   Olmsted. 


30 


APPENDIX  I. 


Amount  and  Imporance  of  Bridge  Traffic. 
Highway  Bridges. 

The  following  table  gives  the  records  of  counts  made  in 
the  fall  of  1909,  and  spring  of  1910  on  the  various  bridges  over 
the  Allegheny  river: 


RECORD  OFCOUNT5 

TA8LC  NO.I. 

3? 

PERIOO 
OPCOl/rtT 

5TRC&T 
CAR^. 

HEAVY 
WAQON9 

LI6HT         CADft,A6c«     AUTO- 
WAGON5    ^                 ~    f^8ILfc5 

P6065- 

61H.0T. 

Aoe.2^  - 

OCT.  23. 

89^!S4 

55J91 

79j247     9534       24£>03 

1.605793 

9TM  5T. 

Aue.26- 
5BPT.  50. 

72,954 

8.961 

14.346       feO           96o 

165.158 

lt.TH.3T. 

OCT.*  - 
OCT.  17 

4,444  " 

7764* 

76.49B, 

50TN.5T. 

At/6.  24- 
OCT.  25- 

9844 

10.104     fr&7         4*i7 

96.4  0£> 

439  5T. 

AU&.2*- 
NOV.  1. 

a«59 

CI65         987         z  73 

150.744 

TA6LE  NO. 

IA/" 

0* 
O0iO««A. 

OP  COUMT     vBMict.es  ' 

Peuvecry      s»Hdus.          POUSLC          peoesTeiAHS 

VCHICLC*.          TRUCKS             TBUCKS                      *—  » 

JTH.  6T. 

Pee.2».            ^OJ 

4^00          2/3         /P35        29,146 

*Automobiles  and  carriages  included  in  counts  for  light  and 
heavy  wagons. 

**Table  IA.  The  count  at  Seventh  street  bridge  was  re- 
corded by  different  units  and  therefore  required  a  separate  table. 
The  Northside  approach  of  this  bridge  was  being  improved  at 
the  time  the  count  was  made,  causing  a  temporary  interference 
with  travel  reflected  in  an  abnormally  small  proportion  of  traffic 
on  the  bridge  and  a  corresponding  increase  for  the  adjacent 
bridges. 

31 


Assuming  that  the  average  number  of  vehicles  per  day 
and  the  average  tonnage  per  day  are  the  same  throughout 
the  year  as  during  the  periods  of  counting,  we  deduce  the 
following  results: 


TRAFFIC   FOR    YEAR 

TABLE    NO.  £. 

I9O9. 

LOCATION    PER 
OP                  O 

8RI06E*     COC 

^0      5TCKT 
HT         CARS 

HfrAW 
WA60/S5 

LIGHT 
WAGOH5 

CA80.MB, 

AUTO- 
MOBJUS5 

TBiArtS. 

fiteoss* 

TOTAL** 

VAL.OE. 

6TH5T.    19 

^9     534.652 

333.629 

474,171 

5/00 

147.095 

9,600.  4o6 

J3.2-<o.oi 

H879./4o,^> 

9TH-5T- 

738,650 

90.  8f2 

!5oA9o 

6205 

9709 

1.877.268 

i4732.i3< 

nWATW0 

|6™-5T 

ft 

M3.85I 

2o2,429 

1991968 

9^754^ 

)02/2o'«37& 

30^51. 

• 

58.8/3 

6q9i9 

3979 

2664 

577.320 

590,43< 

>  44.235  5oo 

43*5T. 

42522 

42559 

5/47 

»  1,351 

691. 

7«o 

5R09C 

32.47fty* 

TABLE    NO.   2  A  """ 

LOCATION    P 
0*  8SI06C5    V 

ASSeH&EB 

'EHICLE& 

VEHlCUfeS. 

TBWCK5. 

Tteuc**         TElArtS- 

3C06S    « 
TOlSrtAQR 

rOTAL    *» 

7TH5T. 

Z9.2/3 

35l,4oo 

0.929 

7^>,E>55  2,127385 

UMoeiu 

k  862,600 

^In  estimating  the  gross  tonage,  the  following  average 
weights  were  used:  a  street  car  with  average  load  — 19  tons; 
a  heavy  wagon  (including  team),  averaging  loaded  and  empty 
vehicles — 4  tons;  a  light  wagon  (including  team),  averaging 
loaded  and  empty  vehicles — 1.75  tons;  an  automobile  or  car- 
riage (including  team), — .9  tons;  pedestrians  and  passen- 
gers are  figured  at  about  150  pounds  apiece. 

**Estimating  heavy  and  light  wagons,  including  team 
and  load  at  $125.  per  ton;  carriages  and  automobiles,  includ- 
ing teams,  at  $300.  per  ton ;  cars  at  $160.  per  ton  and  live  stock 
at  $200.  per  ton,  we  get  an  average  tonage  value  of  $150.  over 
the  Sixth  street,  Seventh  street***  and  Ninth  street  bridges, 
and  $125.  over  the  Sixteenth  street,  Thirtieth  street  and  Forty- 
third  street  bridges. 

***See  Note  under  Table  lA. 


Railroad  Bridges. 

The  bridge  carrying  the  heaviest  traffic  is  that  of  the 
Pittsburgh,  Fort  Wayne  and  Chicago  Railroad,  a  part  of  the 
Pennsylvania  System,  which  forms  one  of  the  links  in  the 
main  line  of  this  railroad  system  between  the  east  and  west. 
Across  this  bridge  are  carried  each  year  about  2,750,000  pas- 
sengers, 32,000  tons  of  mail,  and  53,000,000  tons  of  freight  and 
general  railroad  traffic,  besides  about  2,135,000  pedestrains,* 
making  it  one  of  the  greatest  throats  of  commerce  in  the  coun- 
try. This  is  a  double  deck  bridge  of  4  tracks,  2  tracks  on  each 
deck  with  a  wide  footway  on  the  lower  deck.  It  is  to  be  noted 
that  the  amount  of  traffic  passing  over  this  bridge  is  about  25 
times  as  much  as  that  which  floats  on  the  water  beneath  it, 
and  is  far  higher  in  quality  and  value  per  ton. 

The  other  railroad  bridge  crossing  the  river  within  the 
city  limits  is  the  Thirty-third  street  viaduct  of  the  Baltimore 
and  Ohio  Railroad.  This  is  a  link  in  the  Baltimore  and  Ohio 
Railroad  between  the  east  and  the  west  and  carries  an  enor- 
mous traffic  amounting  each  year  to  about  217,000  passengers 
and  24,330,000  tons  of  freight,  express  and  other  trains. 

Uniting  this  with  the  traffic  over  the  Fort  Wayne  bridge 
of  the  Pennsylvania  we  have  crossing  the  Allegheny  river  on 
the  two  railroad  bridges  a  gross  amount  of  77,330,000  tons, 
and  5,102,000  passengers  and  pedestrians,  with  a  value  of 
tonnage  traffic  estimated  at  approximately  $4,957,000,000. 


*The  figures  for  pedestrians,  passengers  and  general  ton- 
nage are  taken  from  the  affidavit  of  John  C.  Perrott.  The 
tonnage  of  mail  was  obtained  from  the  report  of  the  U.  S. 
Post-office  Department. 


APPENDIX  II. 


Amount  and  Value  of  Allegheny  River  Traffic. 

Dam  No.  i.  The  following  statistics  were  obtained  from 
the  U.  S.  Engineers'  office  and  show  the  number  of  boats,  net 
tonnage  and  number  of  passengers  passing  Dam  No.  i  in  the 
Allegheny  River  during  the  year  1909: 

Table  No.  i. 

Tonnage  of 

Month.             No.  Vessels.  No.  Passengers.      Cargoes. 

January    338  16  30,889 

February    358  18  30,073 

March    1,055  25  81,424 

April     732  197  51,457 

May    896  1,506  57.269 

June      958  1,248  56,324 

July     901  2,495  37388 

August   868  2,019  29,102 

September   1,006  1,681  36,759 

October    955  982  53»622 

November 789  616  42,827 

December    495  231  29,086 


Total 9,351  11,034  536,720 

The  following  are  statistics  of  counts  taken  in  1909  at  the 
different  bridges: 

Table  No.  2. 

Location  of  Period  covered  by  Count        No.  of  Vessels 

Count  Passing 

Sixth  Street  Bridge  Aug.  24th — Oct.  23d  (61  days)  4,534 
Ninth  Street  Bridge  Aug.  26th — Sept.  3Oth  (36  days  3,279 
Fort  Wayne  Bridge  Aug.  2Oth — Oct.  28th  (70  days)  4,925 
Thirtieth  St.  Bridge  Aug.  24th— Oct.  23d  (61  days)  2,022 
J.  R.  R.  Bridge  Sept.  I3th— Nov.  I3th  (60  days)  1,460 

Forty-third  St.  Bridge  Aug.   23d— Nov.     ist     (70    days)     1,580 

Assuming  that  the  ratio  between  the  number  of  vessels 
during  any  given  period  and  the  total  for  the  year  is  the  same 

34 


Location  of 
Count. 

Sixth  St.  Bridge 

Ninth    St.    Bridge.... 

Ft.  Wayne  Bridge 

Thirtieth  St.  Bridge.. 


Vessels. 

Cargoes  &  Cargoes. 

1,097,378 

1,247,020    2,344,398 

1,311,823 

1,484,299    2,796,122 

1,043,020 

1,185,250    2,228,270 

489,416 

556,154     1,045,570 

404,905 

460,119       865,024 

334,6i3 

380,243       714,85.6 

at  all  bridges  as  at  Dam  No.  i ;  and  assuming  that  the  relative 
number  of  different  kinds  of  vessels  are  the  same  at  all 
bridges;  and  further  assuming  that  the  average  weight  of 
cargo  is  the  same  at  all  bridges  as  recorded  at  Dam.  No.  i, 
we  reach  the  estimates  of  total  traffic  under  the  bridges  given 
In  Table  No.  3. 

For  the  Year  1909. 
Table  No.  3. 

No.  of  W'g't  of*  W'gh't  of  Wt.of  Ves.* 
Vessels. 
.'  21,763 
•  25,904 
.  20,685 
9,706 

J.  R.  R.  Bridge 8,030 

Forty-third  St.  Bridge     6,636 

The  largest  total,  that  passing  under  the  Ninth  street 
bridge,  is  without  doubt  somewhat  less  than  the  total  traffic  on 
the  river,  and  a  careful  study  of  the  figures  would  seem  to  in- 
dicate that  the  total  water  borne  traffic  of  the  Allegheny  river  in 
1909  amounted  to  about  one  and  three-quarter  (i£4)  million  tons 
of  cargo  or  three  and  one-half  (3^2)  million  tons  gross  dis- 
placement, including  cargoes,  barges,  tugs  and  all  vessels. 

*The  following  data  as  to  weight  of  vessels  was  kindly 
furnished  by  Mr.  J.  F.  Tilley: 

Weights  of  River  Craft  Without  Freight. 

Medium  tows    800    tons 

Pool  tows  175     tons 

Barges 55     tons 

Coal  boats 105     tons 

Flats 30    tons 

In  estimating  we  assumed  the  following  average  weights 
for  river  craft,  based  in  large  measure  upon  the  above  data : 

Steamboats  225     tons 

Coal  boats  and  barges   80    tons 

Barges    55     tons 

House  boats,  excursion  boats,  yachts 

and  U.  S.  Gov't  boats  45 

Launches,  skiffs,  etc i 

Motor  boats  and  miscellaneous  ....       10 

35 


tons 

ton 

tons 


The  water  borne  commerce  on  this  river  is  of  the  cheap- 
est character  consisting  almost  entirely  of  sand  and  gravel 
dredged  from  the  rivers  and  coal  floated  down  the  Monongahela 
and  delivered  along  the  shores.  All  this  sand,  gravel  and  coal  is 
carried  in  low  lying  barges  or  scows  moved  by  tugs  or  tow- 
boats. 

A  small  amount  of  package  freight  comes  in  and  leaves 
by  packet  boats. 

Table  No.  4. 

(Obtained  from  U.  S.  Engineers). 
Tonnage  Passing  Dam  No.  1  During  Year  1909. 

Coal 231,232  tons 

Other  iron  or  steel  products  ....  428  tons 

Sand    132,894  tons 

Gravel  123,579  tons 

Brick  75  tons 

Stone  3,869  tons 

Timber 8,519  tons 

Lumber    3,5*9  tons 

Pit  posts I3,95o  tons 

Braces  600  tons 

Railroad  ties  6,650  tons 

Wood 45  tons 

General  merchandise 3>II:9  tons 

New  barges  2,628  tons 

New  boats   (coal)    3,94o  tons 

Manure     1,000  tons 

Bark    455  tons 

The  average  value  of  the  freight  based  on  prices  prevail- 
ing in  1910  is  about  $3.00  a  ton.  The  average  value  of  the 
carriers  is  about  $65.00  a  ton.  As  there  is  a  slightly  greater 
weight  of  freight  than  carrier,  an  average  of  $30.00  per  ton 
would  be  a  fair  estimate  of  the  value  of  freight  and  carriers. 
The  total  value  of  the  water  borne  traffic  of  the  Allegheny  river 
for  the  year  under  the  various  bridges  would  be  about  $105,000,- 
ooo. 

The  passenger  traffic  on  the  river  is  so  small  that  it  may 
be  considered  negligible.  It  is  estimated  at  35,000,  largely 
pleasure  traffic  in  small  boats. 

36 


PARIS.  —  Panorama  de  la  Cite,  vue  prise  du  Lou 


Paris  Bridges  and  Boats— Low  Boats  to  Fit  Bridges. 


\'D  fboi. 


A  Typical  Paris  Boat  and  Tows. 


About  one-third  as  much  tonnage  goes  through  Lock  No. 
2  as  through  Lock  No.  I,  and  about  one-sixteenth  as  much 
goes  through  Lock  No.  3  as  through  Lock  No.  i.  There  is 
no  navigation  on  the  river  above  the  third  pool.  It  is  claimed, 
however,  that  with  the  further  canalization  of  the  river  above 
Dam  No.  3  and  the  raising  of  the  bridges  this  traffic  would  be 
greatly  increased.  It  is  to  be  hoped  that  there  will  be  a  con- 
siderable increase,  but  there  are  distinct  limitations  on  the 
probable  amount  of  the  increase.  The  Monongahela  has  a  lar- 
ger and  more  highly  favored  local  territory  to  draw  upon  for 
freight  than  the  Allegheny  so  that  under  the  best  of  condi- 
tions, with  every  possible  improvement  of  navigation,  the 
traffic  on  the  Allegheny  can  never  be  expected  to  approach 
that  upon  the  Monongahela. 

The  total  amount  of  freight  of  all  kinds  passing  Dam.  No. 
i  on  the  Monongahela,  1909,  was  5,417,873,  or  a  little  more  than 
ten  times  the  amount  on  the  Allegheny,  while  the  tonnage  pass- 
ing over  the  Allegheny  bridges  is,  thirty  times  greater  than  the 
tonnage  on  the  Allegheny  river.*  Yet,  if  conceivably,  the 
traffic  on  the  Allegheny  should  equal  that  now  on  the  Monon- 
gahela, it  would  still  be  only  one-third  that  over  the  Allegheny 
bridges. 

Since  the  figures  for  the  present  traffic  over  the  Allegheny 
river  bridges  are  used  for  comparison  with  the  present  river 
traffic,  and  since  the  former  must  continue  to  grow  steadily 
with  the  growth  of  the  Pittsburgh  industrial  district,  it  seems 
quite  clear  that  no  conceivable  growth  in  the  latter  can  seri- 
ously affect  the  overwhelming  predominance  of  the  bridge 
traffic  in  amount  and  value.* 


:See  Diagrams  i,  2  and  3. 


>7 


FOURTEEN  DAY  USE 

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APR  0  5  1992 


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